Device for balancing shafts.



B. GRAEIVHGER.

DEVlCE FOR BALANCING SHAFTS.

APPLICATION FlLED JULY 9.191s.

Patented Mar. 4, 12519.

UNITED STATES PATENT oriuciz.

BENJAMiN GRAEMIGER, or zunrcn, swnzEnLAnn, ASSIGNOR T0 run FIRM or exrmnensnnrscnnrm DER MASCHINENFABRIKEN nscnnn. WYSS & 00., or

ZURICH, SWITZERLAND.

DEVICE FOR BALANCING- SHAFTS.

1,29c,1so.

v Specification of Letters Patent.

Patented Mar; 4, 1919.

Applicat on filed July 9, 1918. Serial no. 244,105.

To all whom it may concern:

Be it known that I, BENJAMIN GRAEMIGER, a citizen of the Republic of Switzerland, residing at Zurich, Hardturmstrasse 19, Switzerland, have invented certain new and useful Improvements in Devices for Balancing Shafts; and I do hereby declare the following to be a clear, full, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawing, and to letters or figures of reference marked thereon, which form a part of this specification..

The invention relates to a device for the axial balancing of the shaft of turbo-blowers and compressors, turbo-pumps, turbines or other similar machines by means of an impeller of an auxiliary centrifugal pump fitted on the shaft to be balanced and supplying a balancingfiuids According to the invention the impeller of such auxiliary pump is designed to act as a balancing disk which forms with the. auxiliary pump casing a pressure chamber connected to two ring clearances, one of which remains constant and the other varies when the shaft is axially displaced.-

A balancing device already known is the one the characteristic feature of which is the fitting of. the impeller of'an auxiliary pump on the shaft of ablower or compressor sothat the axial thrust produced by the pump counteracts the thrust produced by the blower or compressor. Inorder to regu latethe action of the auxiliary pump and adjust its thrust to that of the blower or compressor, a spring loaded throttle valve is fitted on the pressure piping of the aux iliarypump. This valve is not accessible during the running ofthe set, for which reason it mustbe adjusted to a given overpressure before-starting. This entails the repeated stopping and starting of the set until the thrust is approximately balanced. v

V This device ofifers no certainty that the desired balance has been attained or that the; thrust of the blower is exceeded or otherwise and to whatextent. Furthermore, the regulation is dependent on the condition of'the "oil, its temperature and its degree of fluidity.

In contradistiriction, to the above described present invention works automatically and in a thoroughly reliable manner. The use of independent movable valves is completely avoided. The auxiliary pump does not 00- cupy much more room than the above described contrivance and forms a self contained balancing device.

The annexed drawing shows an embodiment of the invention in connection with a two stage rotary blower. The air enters into the blower, through the branch 1, and exhausts through the branch 2. Both runner wheels 3 and 4 are subject to axial thrust, exerted by the air, from right to left. To balance the thrust an auxiliary centrifugal pump is fitted on the high. pressure side,

two separate cycles. In the latter case, the

inner cycle is the one inside the pump which actsas a balancing device,-while the outer one is the one outside thepump, which leads the oil to another point where it is used, for instance, to the bearings and from the latterb'ack to the pump. The im- I peller of theauxiliary pump 8 is provided with blades 9 and isfixed to the shaft 5 which runs in the bearings 6 and 7. Oil is supplied to these runner bladesthrough the suction chamber 10. After leaving the runner blades 9 the oil flows under pressure along two separate paths. One portion reaches the cylindrical ring clearance 11 and y from same flows into the ring chamber 12. The latter is the pressure chamber which is limitedon one sideby the clearance 11 which remains constant when the shaftis axially displaced and on the other side by the clearance 13 which varies when the. shaft is axially displaced. On the right of runner wheel 8,2. e. in the chamber 14 the pressure'is about equal to that in the suction chamber 10. The oil which reaches the chamber 14 from the pressure chamber 12 by passing through the variable clearance 13, flows through the channel 14 back to the suction chamber 10 and begins its cycle over again.

The other portion of the oil which leaves to the suction chamber of the pump. In

this manner the outer cycle is closed.

The runner wheel 8 of the auxiliary pump is subject to a' side thrust from the left 'to the right, owing to the overpressure 'of the oil in the side chambers 21 and 12. The pressure in chamber 21 varies very little during the running of the pump. On the contrary, the pressure in the chamber 12 varies considerably, because-thesection of its outlet 13 varies also considerably owing to theaxial displacement of the shaft. When the blower is running under constant pressure, the shaft 5 automatically takes up such a position that the pressure which is produced in the ring chambers 21 and 12, exerts on the runner wheel 8 a side thrust from the left to the right which balances the side thrust acting upon the runner Wheels 3 and 4. I

As shown on the drawing, the whole balancing device is simple and perfectly safe in working.- For the purpose of better illustrating the invention the pump, in proportion to the blower, has been-designed on a larger scale. In actual practice, however, the pump would occupy considerably less room. 4 Y

and with a variable clearance, are already known but the required oil pressure is produced by a pump arranged outside of the machine. The advantage of the invention consists in the compactness of the auxiliary pump and balancing disk, whereby space and manufacturing costs are reduced. In addition to this, the machines are more easy to watch and are safer in working.

What I claim is:

1. In a device for the axial balancing of the shaft of turbo-blowers or compressors, turbo-pumps, turbines or other simllar machines, in combination: an auxlllary centrifugal pump, the im eller of wh1ch 1s fitted on the shaft to be alanced, a pressure chamber formed by the auxiliary pump casing-with this impeller Wh1ch' acts as a balancing disk, two ring clearances connected with said pressure chamber, oneof these clearances remaining constant and the other Balancing disks working with a-constant' varying when the shaft is axially displaced, substantially as set forth.

2. In a device for the axial balancing of the shaft of turbo-blowers or compressors, turbo-pumps, turbines or other similar machines, in combination: an auxiliary centrifugal pump, the impeller of which is fitted on the shaft to be balanced, a pressure chamber formed by the auxiliary pump casing with this impeller, a ring clearance connecting the outlet of the impeller blades with the pressure chamber, said clearance bein cylindrical and concentric with the axis 0 the pump, and another ring clearance connected to the pressure chamber, said ring clearance being perpendicular to the axis of the pump, substantially as set forth.

3. In a device for the axial balancing of the sh'aftof turbo-blowers or compressors, turbo-pumps, turbines or other similar machines, in combination: an auxiliary centrifugal pump, the impeller of which is fitted on the shaft to be balanced, a pressure chamber formed by the auxiliary ump cas ing'with the impeller, said cham er being connected with the outlet of the impeller blades through a cylindrical clearance concentric with the axls of the pump, a second clearance perpendicular to the axis of the pump connectmg the pressure chamber with a chamber formed in the pump casing behind theimpeller, said chamber being connected with a suction chamber before the impeller, substantially as set forth.

fitted on the shaft to be balanced, a pressure chamber formed by the auxiliary pump casing withthe impeller which acts as a balancing disk, two ring clearances connected with c said pressure chamber, one of these clearances remaining constant and the other varyingwhen the shaft is axially displaced, a chamber formed in the pump casing behind the impeller, said chamber being connected with the pressure chamber by means of the variable clearance, a connection between the chamber behind the impeller and a suction Ichamber before the impeller, substantially as BENJAMIN GRAEMIGER. 

